The late Teddy Kennedy wrote in True Compass, a posthumous memoir that will be released this month, that he “made terrible decisions” regarding the Chappaquiddick incident in 1969, in which young campaign worker Mary Jo Kopechne was found drowned in his car, after he careened off a bridge.

Kennedy didn’t give any new insight into the incident, but he did call his behavior “inexcusable,” and said the stress arising out of the incident likely shortened the life of his then-sick father, Joseph. Pundits point to the incident as the reason Teddy Kennedy was never a serious presidential candidate, as the New England native lost the nomination in 1980 to the incumbent, Jimmy Carter.

Other starling revelations in the forthcoming 532-page book include: his longtime battle with what he tabbed “self-destructive drinking;” his acceptance of the Warren Commission’s findings in his brother John’s assassination; said brother John “was increasingly convinced that the conflict (in Vietnam) could not be resolved militarily” and that he reassured then-Pres. Bill Clinton he would support him during the Monica Lewinsky fiasco.

The longtime Massachusetts senator died Aug. 25 at 77, after battling brain cancer for a year.